By Richard Ehrenberg. Copyright
© 1999 Richard Ehrenberg and Harris Publications. Used by
more muscle car action, read Mopar Action!
It wasn't all that many years ago. You wanted to go fast in your Mopar,
so you dragged a set of the "best" big block street castings, the
trusty 906s, down to the basement, and hogged the ports out to
tree-trunk size. Of course, you didn't waste any time on the
"meaningless" bowl area. If you were lucky, after a
week of breathing iron filings, maybe the car only went a tenth
Then came the 1970s. Flow benches
began to appear at some better equipped shops, and aftermarket heads
began to emerge, such as the Zeeker big-block pieces, aluminum Hemi
heads (even dual plug) and the factory's own Stage 4 iron big-block and
W-2 small-block pieces. Soon, the aftermarket began duplicating the
W-2s in aluminum, and, voila! A trickle of heads became an open
floodgate. B-1 and Indy heads came on-line for big blocks, and we even
saw Hemi heads designed to bolt up to wedge blocks. Small block lovers
weren't forgotten, as the factory's W-5 aluminum castings filled a void.
were satisfied? Never! We want new iron Hemi heads! New Max Wedge
heads! Affordable aluminum small block sportsman heads!
And...and...well, you get the picture.Sure enough, our
prayers have been answered. Whereas 20 years ago the heads on your ride
were almost guaranteed to be the factory-stock castings, today your
choices are seemingly limitless. In fact, in the last year alone, a
whole flock of new heads designed for your Pentastar powerplant have
surfaced. Therefore, we figured this would be an ideal time to pursue
these new offerings for Plymouth, Dodge, and Chrysler.
Since "the factory" is where it
all started, we figured: what better place for us to begin? And, with
the elephant motor the spiritual leader of all that is Mopar, it should
rightfully receive priority treatment. The factory apparently agreed,
as it has re-issued an updated version of the famous Street hemi iron
monsters (fig. 1). These castings, available as part number P4529828,
are 100% interchangeable with '66-71 castings (right down to using the
same casting number), which is certainly not a bad thing. Stock
2.25/1.74", 5/16"-stem valve, are accommodated, and the chambers are
virtually identical to the oldies, at 173-175cc
beauties are, to our mind, being produced not a second too soon, as the
supply of decent used iron heads, last produced in 1971, has dwindled
to a precious few, and that scarcity has called up the ol' law of
supply and demand. In other word, the used iron was priced like gold.
content to rest on their laurels, the MP team saw fit to include enough
additional material in the updated castings to allow those so inclined
to modify the ports for significantly better flow numbers than the
original, classic piece. Right out of the box, they outflow their
predecessors, in spite of having slightly less port volume. Another
worthwhile virtue is that additional material has been added to
critical areas that were crack prone in the older heads (in
super-high-output applications). Three cheers for MP!
second new head from Mopar Performance isn’t truly new.
Rather, it’s a re-issue of a once popular head
that’s been missing in action since 1488: the Stage V (that's
five for you Arabic-number fans) iron head. This is a slick piece,
equally at home cruising on the streets or blasting down the quarter
mile. Its claim to fame is its improved flow numbers while maintaining
100% interchangeability with all earlier cast-iron production (i.e.,
non=max wedge) heads. In other words, bolt on a pair and go-fast.
the heads were last seen six years ago, there were two-versions
available: a stock replacement version and a ported, big-valve bracket
setup. Neither utilized hardened exhaust valve seats, making them
unsuitable for no-lead fuels Today's catalog lists no fewer than four
versions- something for everyone. The service replacements
head, which is machined for stock 2.08/1.74” valves, happily
is now produced with production-type induction hardened valve seats.
It’s available as part number P4529992, and despite big flow
improvements over late big-block heads, is being billed as an emissions
legal part. It’s this version which will potentially have the
most impact on Chrysler's drag racing effort: as of this past January,
NHRA has accepted the 992 as a replacement casting for all '68-'78
bigblock S/S applications! Way to go, NHRA!
like to just open the box and bolt 'em on, you can specify P5249114.
This will bring you a set of 992s, assembled with single springs and
the motor home Viton seals, along with the 2.08/ 1.74" valves. In other
words, it's like a complete production 906 head assembly, but with
better flow and hard seats. Somebody up there must be listening to our
prayers after all
Third in the MP a la carte
big-block main-course section is the P4529993. Starting with the same
casting as the “992” version, it’s
machined for mega 2.14/1.81” valves, and, in the process, the
hardened valve seat area is lost.
absolutely not least on the menu is the P5249112 ported
version. Specifying this number will bring you a ported, race
–ready version, big valves, 077 dual springs, Perfect Circle
Teflon seals, chrome-moly retainers, and hardened keepers. These
race-ready beauts are quoted by MP as offering a 15% flow gain over
as-cast Stage Vs-certainly nothing to sneeze at.
last in the saga of MP heads is, in reality, also not quite new: the
Stage VI aluminum big-block piece. We covered this head in intimately
in the February, 1993 issue, so we won't go into macrodetail here.
Suffice to say that the Stage 6 is a thoroughly modern head, penned
in-house by Chrysler Engineering. The bare head, P4529335, is designed
to use as many stock parts as possible, including valves, rockers,
headers; etc., while attaining big numbers. The six's rely on what has
to be the cylinder head trick of the decade: since it's well known that
raising the intake ports gives the mix a straighter shot at the bowl,
the Chrysler crew raised the intake a whole bunch. Uh, special intake
manifold required, right? Wrong! Just bolt the heads on your 383/400
low-deck block, then bolt up a stock 440 ("RB") manifold. Trick! (Usage
on a 440 requires that set of P5249189 spacers be utilized.)
real news about the Stage VI is just how much horsepower can be made
with them. The limiting factor would seem to be the stock port window,
but looks can be deceiving. The crew at Muscle Motors in Lansing,
Michigan ((517] 482-4900) has built a Daytona Super Pro car as a
rolling test bed for their Stage VI development work. Using a single
four barrel carb, the 2200-pound car has gone a best of 8.45 secs. at
161 MPH, without ever seeing the high side of 7,000 RPM. This takes
some serious power (over 700 ponies, in fact), which, in turn, takes
some equally serious airflow through the heads. While MP offers ported
6s (P5249113), these guys wanted more-much more. How much is much?
Well, take a look at this chart (intake).
is one last version of the Stage 6 head available, and it's for the
hardest of hard-core racers only. P4349600 will bring you a bare
unmachined (for guides) casting, allowing the daring, creative types to
experiment with almost unlimited freedom.
drive away from the factory, we should mention that Mopar Performance
is hard at work on a successor to the W-5 aluminum A-engine race heads.
An all-new design, the latest castings will be known as W-7s. Utilizing
a small high-swirl chamber and Jessel-type rockers, this promises to be
a big step forward for SB Mopar Racers. As this is written, Ritter and
Weber are running a preproduction pair on their killer Daytona. Watch
this space for a full story on these in the very near future.
would love to run W-5s on their smallblock, sure! But W-5s take unique
valve gear, intakes, and, usually, headers. Read: expensive! So
Brodix's Dave Rotter teamed up with the B-1 crew (Wayne County Speed
Shop and Koffel's Place) and formulated a completely new A-motor head,
and tagged it with the confusing name, B1-BA. Cast in weight-saving
aluminum, this head was designed to fill the gap between the production
castings and the all-out MP stuff. As a bonus, the B1-BA is capable of
utilizing nearly any rocker arm configuration on the planet, from
stock-based shafts to the trick Jesel pieces (see fig. 5), which are
available in a candy-store variety of ratios. And, yes, the B1-BAs can
even be fitted with the AMC/Viper late-model stud-mounted rocker setup.
Plus, the heads can be used on the Mopar Performance R-block, which, in
most versions produced to date, oil through the pushrods like
late-model Magnum truck motors.
The B1-BA is equipped with
modern high-swirl 65cc chambers, and are fitted with generous 2.08"
intake valves. The deck surface is significantly beefed (triangulated
is the word Dave Koffel uses) to prevent the cracks that have been
known to occur in this area on megapower applications. As an additional
concession to crack residence, the deck surface of the new castings is
a full 3/4" thick. The intake side is now almost totally free of the
pushrod bulge that has driven SB Mopar porters nuts for decades. The
exhaust side hat also received a considerable amount of attention, with
the ports no longer being saddled with the dogleg, and are raised 0.25"
for a straighter shot.
Other features of the new
B1-BAs are standard-equipment 11/32" guide diameters, and the famous SB
Mopar 18-degree valve inclination.
testing of heads is akin to opening Pandora's box, we nonetheless
decided to tough it out and have a set of box-stock castings, which we
borrowed from Dave Koffel, flowed on a local shop's SuperFlow bench. As
has become the standard procedure here at Mopar Action, we asked guys
shop (FIowTech of Yorktown Heights, NY 
962-1325) to use 10" of depression. We like the 10" numbers, as we feel
that this is more like what a real race motor will use, and SuperFlow
uses this depression in nearly all of their engineering examples. If
you're more attuned to the big numbers produced by using 28"
depression, no sweat. Just remember that the 136.3 figure (at 0.60"
lift) converts to a whopping 227.6 at 28" According to the very
conservative figures provided by SuperFlow, this flow is adequate to
feed a 465 horsepower smallblock mill, and this, with virtually as-cast
Thus, it's very important to remember that
these new B1-BA heads from Brodix, like all aluminum heads, are very
easy to modify the big BIG numbers. That's the beauty of aluminum.
Mistake? No Problem! A quick weld and try again. Of course, with a
rock-solid platform like this to work with, the porter's job becomes
that much easier.
Cylinder Head Company has become famous for ...yup, you guessed it,
Indy cylinder heads. The main product in the Indy line is a neat
aluminum casting that, for the most part, duplicates the dimensions of
the original '63'64 max wedge piece. Now, Indy wows us with a cast iron
version of their design.
Billed as a Stage
III max wedge replacement, the Indy nonetheless deviates from the
original Chrysler design in several key areas:
All of these features
make this casting one that should have the potential for significantly
more flow (i.e., power) than the original maxi. Yet, it utilizes stock
rockers, valve covers, manifolds ...even stock gaskets. And, of course,
the durability and low-rev torque characteristics of good ol' grey cast
iron make the Indy a seemingly ideal choice for an economical killer
street motor. In addition, one wanting to create a max wedge lookalike
could save significant time and money by opting for the Indys instead
of searching for an ancient set of gennie castings of dubious quality.
by Rick Ehrenberg, click here!
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